1. Field of the Invention
The present invention relates to a printing mask for printing circuits with on a board having irregularities and a process for producing such a mask.
2. Description of the Prior Art
In case of forming a circuit on a board by means of printing, a printing mask has conventionally been used. Such printing mask has been made by forming a pattern to be printed on a cloth screen of silk, nylon or other sythetic fibers or alternatively on a stainless steel screen, the screen being tensed on a frame. Then, upon printing a circuit, the entire surface of the printing mask is in contact with the surface ofthe board. Therefore, if the board has a projecting portion, it has been impossible to print on it by using the printing mask of the above type. However, the present inventor has noted that if only a part of the printing mask having that pattern on it can fit on the surface of the board, it is not always necessary to press against the entire surface.